Mechanics of aligned carbon nanotube polymer matrix nanocomposites simulated via stochastic three-dimensional morphology
Mechanics of aligned carbon nanotube polymer matrix nanocomposites simulated via stochastic three-dimensional morphology
复制标题
通过随机三维形态模拟定向碳纳米管聚合物基纳米复合材料的力学
作者：
Itai Y. Stein;B. Wardle
增强和定制性能的前景推动了对一维纳米材料的研究，特别是用于增强聚合物材料的定向碳纳米管（A-CNT）。虽然碳纳米管具有显着的理论性能，但之前关于定向碳纳米管聚合物基纳米复合材料（A-PNC）的研究报道的机械性能比混合物规则预测的机械性能低几个数量级。这种巨大差异主要源于 CNT 的形态，因为构成 A-PNC 的 CNT 具有显着的局部曲率，通常称为波纹度。在这里，我们提出了一个模拟框架，能够分析 105 个具有真实三维形态的波状 CNT，以量化波状对波状 CNT 有效弹性模量贡献的影响。模拟结果表明，由于增强 CNT“纤维”的剪切模量较低，并且剪切变形模式的柔量贡献较大 (> 50 % ?> )，波纹度使 A-CNT 的有效刚度贡献降低了两到三个数量级。此外，模拟框架产生的机械性能预测优于之前使用有限元分析报告的机械性能预测，因为需要对形态的代表性描述来准确预测 A-PNC 的性能。计划进一步开展量化 A-PNC 三维形态、模拟其完整非各向同性本构关系并预测其失效机制的工作。
The promise of enhanced and tailored properties motivates the study of one-dimensional nanomaterials, especially aligned carbon nanotubes (A-CNTs), for the reinforcement of polymeric materials. While CNTs have remarkable theoretical properties, previous work on aligned CNT polymer matrix nanocomposites (A-PNCs) reported mechanical properties that are orders of magnitude lower than those predicted by rule of mixtures. This large difference primarily originates from the morphology of the CNTs, because the CNTs that comprise the A-PNCs have significant local curvature commonly referred to as waviness. Here we present a simulation framework capable of analyzing 105 wavy CNTs with realistic three-dimensional morphologies to quantify the impact of waviness on the effective elastic modulus contribution of wavy CNTs. The simulation results show that due to the low shear modulus of the reinforcing CNT ‘fibers’, and large ( > 50 % ?> ) compliance contribution of the shear deformation mode, waviness reduces the effective stiffness contribution of the A-CNTs by two to three orders of magnitude. Also, the mechanical property predictions resulting from the simulation framework outperform those previously reported using finite element analysis since representative descriptions of the morphology are required to accurately predict properties of the A-PNCs. Further work to quantify the morphology of A-PNCs in three-dimensions, simulate their full non-isotropic constitutive relations, and predict their failure mechanisms is planned.